#!/usr/bin/perl
use strict;
use warnings;

# 1) get actual referer path name (strip server part)
my ($pagename, $client) = ($ENV{HTTP_REFERER}, $ENV{REMOTE_ADDR});
$pagename = $1 if $pagename =~ m{ ^\w+:// [^/]+ / (.+)$ }x;

# 2) update db and get count value
my $count = handledb($pagename, $client);

# 3)write results
++$|; binmode STDOUT;
print counterimage(48, 15, $count, 'blue', 'white'); # expect 6x13 font

# Subroutine handledb()
# update database stuff, return number hits of a site (link)
#
sub handledb {
 use DBI;
 my ($page, $client) = @_;
 my $dbhost = 'my.glory.host.com';
 my ($dbn, $usr, $pw) =('counting', 'db-username', 'db-password');
 my $ignoredreferer = '192.168.1.2';
 
 my $dbh = DBI->connect("dbi:mysql:$dbn:$dbhost", $usr, $pw) || die "$DBI::errstr!";
 my $item = $dbh->quote($page);
 
 my $query = 'INSERT IGNORE INTO counters (pagename) VALUES (?)';
 my $sth = $dbh->prepare($query); $sth->execute( $item );

 if( $client ne $ignoredreferer ) { # don't count on this referer
    $query = 'UPDATE counters SET pagecounter = pagecounter + 1 WHERE pagename = ?';
    $sth = $dbh->prepare($query); $sth->execute( $item );
 }
 
 $query = 'SELECT pagecounter FROM counters WHERE pagename = ?';
 $sth = $dbh->prepare($query); $sth->execute( $item );
 
 my ($nhits) = $dbh->selectrow_array($sth);
 $dbh->disconnect or warn "Disconnection failed: $DBI::errstr!\n";
 
 return $nhits;
}

# Subroutine counterimage()
# returns a buffer containing an (binary) image of the number
# (in .png format) wanted plus it's corresponding http content header
sub counterimage {
 use Imager;
 my ($lx, $ly, $text, $color, $bgcolor) = @_;
 my $img = Imager->new(xsize => $lx, ysize => $ly, channels => 3);
 my $fnt = Imager::Font->new(file  =>'/usr/share/fonts/misc/6x13B.pcf.gz'); 

 $img->box(filled=>1, color=>$bgcolor);
 $fnt->align(image  => $img, x => $lx/2, y => $ly/2,
             string => $text,
             color  => $color,
             halign => 'center',
             valign => 'center'
            );
 my $data;
 $img->write(type=>'png', data=>\$data) or die $img->errstr;
 return "Content-type: image/png\n"
      . "Content-Length: " . length($data) . "\n\n"
      . $data;
}